A filter cartridge for the filtering of water to remove particulates therefrom, for the filtering of chemical slurries, for the filtering of hydrocarbons such as oils or the like to eliminate particulates therefrom, e.g. in motor vehicle recirculating oil systems, generally comprises a support structure and at least one filter layer carried by the support structure and designed to trap particulates. The support structure can be designed so that liquids can be sucked into the interior, forced through the interior or otherwise so as to cause the liquid phase to penetrate the filter layer and allow particulates to deposit thereon.
It has been proposed to provide the filter layer as a wire mesh or fabric and to form the filter layer around a generally cylindrical and fluid-permeable support which may be tubular so that the interior or support body forms a passage. The wire mesh or fabric can be seamed or provided in a multiplicity of turns in a spiral pattern and, to increase the area per unit volume, can be "folded".
The term "folded" is used here to refer to a corrugated pattern of the filter layer so that, for a given diameter, the available filtering surface is greater than that of a corresponding right circular cylinder.
It has also been proposed to provide filter layers of sintered material, i.e. a porous mass of particles which are fused together so as to retain the porosity. Such a filter layer has advantages over a wire-mesh or fabric filter in that the pores can be more readily controlled smaller, the filter layer is more capable of withstanding chemical stress and hence high pressure differential, and depending upon the material from which the filtered layer is constituted, the filter can be more resistant to chemical attacks and other effects including temperature. As disclosed in German GEBRAUCHSMUSTER DT-Gbm 1872428, such sintered filter layers have invariably been cylindrical and provided upon a cylindrical support.